【C20】A．beforeB．whenC．sinceD．until

【C20】A．whileB．forC．afterD．until

【C2】A．BeforeB．OverC．SinceD．From

【C19】A．beforeB．afterC．onD．until

I was watching TV_____ the telephone rang.A. whileB. whenC. since

【C5】A．beforeB．thatC．soD．until

【C7】A．beforeB．untilC．afterD．since